Aircraft provided with a gun



Sept. 17, 1935. M. BIRKIGT AIRCRAFT PROVIDED WITH A'GUN Filed Sept. 20.1934 Patented Sept. 1,7, 1935 2,014,876 AIRCRAFT PRovmEn yWIII'II A GUNMarc Birkin, Bois-Colembes, France Application 6 Claims.

The present invention relates to aircraft provided with a gun adapted toshoot in the direction of the axis of revolution of a propeller.

The object of the present invention is to attenuate the effect of recoilof guns so fitted on an aircraft.

The essential characteristic of the present invention consists inproviding guns mounted in this manner on an aircraft with a muzzlerecoil apparatus which is disposed in front of the propeller (withreference yto the direction in which the gun is to shoot).

Other characteristics of the present invention will result from thefollowing detailed description of an embodiment thereof. v

A preferred embodiment of the present invention will be hereinafterdescribed, with reference to the accompanying drawing, given merely byWay of example, and in which:

The only figure is a vertical sectional view, on a line passing throughthe axis of revolution of the propeller, of the front 'part of thefuselage of an airplane fitted with a gun in the manner above referredto, according to the present invention.

In the specific embodiment which will be hereinafter described, it hasbeen supposed that the airplane is provided with a single engine drivingthe propeller through which the gun is to shoot.

As far as this airplane is concerned, the general arrangement. with theexception, of course, of the gun itself, may be of any conventional orother kind. For instance, it includes, at the front part of the fuselageI an engine 2 adapted to drive, through a suitable reducing gear 3, atubular shaft Il, which is not in line with the axis of the crankshaftof the engine and to ywhich is secured a propeller 5.

Concerning now the gun, it can be fixed in any suitable manner, known initself, to the casing of the engine, for instance by providing at thefront end of tube 6 of said gun a groove 1 capable of being fitted,after mounting of the parts, in a corresponding hole provided in thecasing of the engine. In any case, the parts are assemb'led in suchmanner that the gun canshoot through tubular shaft 4. Finally, tube 6 isprolonged, toward the front, beyond the hub of propeller 5 for instanceby fixing thereto a tube 8 -acting as a `protection against the flamesescaping from the `muzzle of the gun.

It should be well understood that the whole arrangement above describedis already known per se.

According to the present invention, this arrangement is completed byproviding the gun 6 september 2o, 1934, serial No. 744,821 In FranceMarch 1, 193.4

with a muzzle recoil sysetm which is located in front of the propeller5.

Advantageously, this recoil device is xed either to the extremity oftube 6 if the latter extends suliiciently far in a forward direction, orto the 5 tube 8 above referred to.

The recoil device illustrated in the drawing consists essentially of awall 9 which is located opposite the orifice of tube 6 or of the tube 8attached to said tube 6 (for instance ata distance l0 from said orificeequal to four times the caliber of said projectile). This structure 9 isprovided with a hole I0 locatedin such'manner that the projectilesissuing from said tube can pass through said hole. 'Ihis hole Ill ismade of such 'l5 a diameter that when a projectile Il is passingtherethrough this hole I0 is fully stopped by said projectile.

Thus, when a projectile is passing through this hole Ill, the burntpowder gases issuing from the 20 muzzle of the gun cannot escape throughsaid hole and therefore strike wall 9, thus producing a thrust directedtoward the front and which balances, to a certain degree, the rearwardlydirected thrust that is produced by the recoil of the 25 gun.

Of course, according -to the present invention,

the muzzle recoil device may be given any suitable shape whatever.

However I have found that the specific arrange- 30 ment illustrated bythe drawing is -particularly advantageous for practical purposes.

According to this arrangement, the central portion of wall 9 is giventhe shape of a body of revolution such that the edge of hole Ill is sub-35 stantially tangential to the trajectory of the projectiles, this wall9 then curving progressively, in the shape of a portion of a tore (asshown in the drawing), its periphery being directed toward the rear ofthe. airplane. Consequently, with such an arrangement. wall 9constitutes a kind of 'deflector, in the shape of a body of revolution,which causes the gases issuing from thev muzzle of the gun=to finallyescape towardsthe rear, without producing any shock. The reaction ofthese gases upon'wall 9, while they are being deflected produces theforward thrust exerted on said wall 9, as above explained.

In order to better guide the burnt gases, a sec- 50 ond wall I2 isprovided. This second wall can be fixed directly to the end of tube 6'or tube 8 as the case may be. It is located on the inside of the kindof cap formed by the wall 9 above referrel to, and vat a suitabledistance from said 55 tangent atthe front and two .branches extending-Athe rear edge of walls 9 and wall 9 for permitting a satisfactory flowofthe gases.

With this arrangement, wall 9 can be fixed in the desired position, atthe desired distance from the muzzle of the gun, by means of ribs I3,for instance radially disposed, which connect said wall 9 to wall l2. Asabove stated, this wall l2 is directly fixed to the muzzle of the gun.

Although wall 9 may be given any desired external shape, I have foundthat it is particularly advantageous to give it approximately the shapeof a cone, thusforming, at the front end of the fuselage a streamlinestructure.

Ithen fix to propeller 5 a ring Il in the shape of a frustum of a cone,arranged to revolve together with the propeller and such that its rearedge is located opposite the front edge of the fuselage while its frontedge is located .close to The whole of the external wall of thedefleotor 9-I2 above described, of the revolving ring I4 fixed to thepropeller, and of the front part of the fuselage can thus be given asubstantially ovoid shape as best suited to a good penetration into air.

However, preferably, I give the rear edge of wall 9 a diameter slightlylarger than that of the front edge of ring-shaped element I4, in orderto leave between these two elements an annular passage of a width equalto some centimeters, through which the burnt powder gases can escapetoward the rear.

'Ihe arrangement above described is particularly simple and it permitsof combining the advantages of a muzzle recoil device for checking therecoil of the gun with4 those of a streamline structure as perfect aspossible of the front portion of the fuselage of the aircraft.

While I have described, what I deem to be practical and efficientembodiments of the present invention, it should be well understood thatI do not Wish to be limited thereto as there might be changes made inthe arrangement, disposition and form of the parts without departingfrom the principle of the present invention as comprehended within thescope of the appended claims.

What I claim is:

1. In an aircraft including a fuselage, a propeller provided with ahollow hub and a hollow shaft for driving said propeller, thecombination of a gun adapted to shoot through said hub along the axis ofsaid shaft in a frontward direction, a deilector located in front ofsaid propeller, the

^ internal wall of said deector having the shape of la surface ofrevolution about said axis the generatrix of which is a curve having avertical both in a rearward direction, one of said branches beingtangent at its end to the path 'of travel of the projectiles issuingfrom said gun other branch extending outwardly to a greater distancetoward the rear, and a ring-shaped wall mounted about the axis of saidpropeller so that its rear edge is in line with said fuselage and itsfront end is of a diameter slightly smaller than that of the rear edgeof the outer wall of said deector. I

2.4111 an aircraft including a propeller having a hollow hub and ahollow shaft for driving said propeller, the combinationof a gun adaptedto shoot along the axis of the 'shaft of said propeller in a forwarddirection, with a combined recoil ,and the Apowder gases to directcompensating device and air resistance reducer comprising asubstantially conical member located in front of the propeller with itsapex forwardly, said member having a hole therein for the passage of aprojectile, the size of said member being vsuch that its outer surfacedirects the air in a streamline with the outer surfaces of that portionof the aircraft directly to the rear of the propeller.

3. In an aircraft including a propeller having a hollow hub and' ahollow shaft for driving said propeller, the combination of a gunadapted to shoot along the axis of the shaft of said propeller inforward direction, with a combined recoil compensating device and airresistance re ducer, said combined device and reducer comprising asubstantially conical sheet metal member rigid with said aircraft andlocated in front of the propeller with its apex forwardly, said memberhaving a hole therein for the passage of a projectile, portions of saidmember around the hole extending first forwardly inthe direction of theaxis, then outwardly and away from the axis and then rearwardly to catchthe force of the them rearwardly, the size of said member being suchthat its outer surface directs the air in a streamline with the outersurfaces of that portion of the aircraft directly to the rear of thepropeller.

4. In an aircraft including a propeller having a hollow hub and a hollowshaft for driving said propeller, the combination of a gun adapted toshoot along the axis of said shaft in a forward directiony with acombined recoil compensating device and air resistance reducer locatedin front of the propeller and rigid with said aircraft and composed oftwo substantially conical members spaced from each other, both of saidmembers having openings therein for the passage of a projectile, saidmembers forming a rearwardly extending passage of annular cross section,the size of the outer member being such that its outer surface directsthe air in a .streamline with the outer surfaces of that portion of theaircraft directly to the rear of the propeller.

5. In an aircraft including a propeller having a.hollow hub and a hollowshaft for driving said propeller, the combination of a gun adapted toshoot along the axis of said shaft in forward direction, said gun havingan extension projecting forwardly of said propeller, with a combinedrecoil compensating device and air resistance reducer, said combineddevice and reducer comprising at least two substantially conical memberslocated in front of theA propeller and spaced from each other, both ofvsaid members having openings therein for the passage of a projectile and-formingfa-rearwardly extending passage of annular cross section, theinner member being secured to. the extension on said gun' through whichthe projectile passes, and the outer member being secured tosaid innermember, the outer member being of such size that its outer surfacedirects the air in a streamline with the outer surfaces of that portionof the aircraft directly to the rear of the propeller.'

6. In a combination as defined in claim 4, a frusto-conical shieldpositioned between said device and the propeller and mounted to rotatewith l

